Lab part 2

Five Kingdom Classification System

Once upon a time, all living things were lumped together into two kingdoms,
namely plants and animals (at least, that's how I learned it). Animals
included every living thing that moved, ate, and grew to a certain size
and stopped growing. Plants included every living thing that did not
move or eat and that continued to grow throughout life. It became very
difficult to group some living things into one or the other, so early
in the past century the two kingdoms were expanded into five kingdoms:
Protista (the single-celled eukaryotes); Fungi (fungus and related organisms);
Plantae (the plants); Animalia (the animals); Monera (the prokaryotes).
Many biologists now recognize six distinct kingdoms, dividing Monera
into the Eubacteria and Archeobacteria.

All I can say is that the sytem holds true for this week, at least.
It might even hold up for a century or two. Accepted systems of classification
have changed at a far faster pace than the species have taken to evolve,
that's for certain.

Kingdoms are divided into categories called phyla, each phylum is divided
into classes, each class into orders, each order into families, each
family into genera, and each genus into species. A species represents
one type of organism, such as dog, tiger shark, Ameoba proteus (the
common amoeba), Homo sapiens (us), or Acer palmatum (Japanese
maple). Note that species names should be underlined or written in italics.

Classifying larger organisms into kingdoms is usually easy, but in
a microenvironment it can be tricky. If you have had a little biology,
a good exercise is to describe individual living things, and to try to
classify them as to kingdom.

Monera (includes Eubacteria and Archeobacteria)

Individuals are single-celled, may or may not move, have a cell wall,
have no chloroplasts or other organelles, and have no nucleus. Monera
are usually very tiny, although one type, namely the blue-green bacteria,
look like algae. They are filamentous and quite long, green, but
have no visible structure inside the cells. No visible feeding mechanism.
They absorb nutrients through the cell wall or produce their own
by photosynthesis.

Protista

Protists are single-celled and usually move by cilia, flagella, or
by amoeboid mechanisms. There is usually no cell wall, although some
forms may have a cell wall. They have organelles including a nucleus
and may have chloroplasts, so some will be green and others won't
be. They are small, although many are big enough to be recognized
in a dissecting microscope or even with a magnifying glass. Nutrients
are acquired by photosynthesis, ingestion of other organisms, or
both.

Fungi

Fungi are multicellular,with a cell wall, organelles including a
nucleus, but no chloroplasts. They have no mechanisms for locomotion.
Fungi range in size from microscopic to very large ( such as mushrooms).
Nutrients are acquired by absorption. For the most part, fungi acquire
nutrients from decaying material.

Plantae

Plants are multicellular and most don't move, although gametes of
some plants move using cilia or flagella. Organelles including nucleus,
chloroplasts are present, and cell walls are present. Nutrients are
acquired by photosynthesis (they all require sunlight).

Animalia

Animals are multicellular, and move with the aid of cilia, flagella,
or muscular organs based on contractile proteins. They have organelles
including a nucleus, but no chloroplasts or cell walls. Animals
acquire nutrients by ingestion.

A "mini-key" to the five kingdoms

Suppose you see something in freshwater that certainly appears to
be living. How can you begin to determine what it is? Here is a key
(not quite perfect) that you might use to help determine the kingdom
to which it belongs.

1. Is it green or does it have green parts?

Yes - go to 2

No - go to 3

2. Could be a plant or a protist, or blue-green bacteria. Make
sure that the green is really part of the organism, though. An
animal might have eaten something green, for example.

Single-celled? go to 6

Multicellular? Plantae. Look for cell walls, internal
structure. In the compound microscope you might be able
to see chloroplasts.

4. Could be a moneran or a protist. Can you see any detail
inside the cell?

Yes - Protista. You should be able to see at least a
nucleus and/or contractile vacuole, and a definite shape.
Movement should be present, using cilia, flagella, or amoeboid
motion. Cilia or flagella may be difficult to see.

No - Monera. Should be quite small. May be shaped like
short dashes (rods), small dots (cocci), or curved or spiral
shaped. The largest them that is commonly found in freshwater
is called Spirillum volutans. It is spiral shaped, and
can be nearly a millimeter long. Except for Spirillum,
it is very difficult to see Monerans except in a compound
microscope with special lighting.

5. Animalia or Fungi. Is it moving?

Yes - Animalia. Movement can be by cilia, flagella, or
complex, involving parts that contract. Structure should
be complex. Feeding activity may be obvious.

No - Fungus. Should be branched, colorless filaments.
May have some kind of fruiting body (mushrooms are a fungus,
don't forget). Usually attached to some piece of decaying
matter - may form a fuzzy coating on or around an object.
In water, some bacterial infections of fish and other animals
may be mistaken for a fungus.

6. Most likely Protista. If it consists of long, unbranched
greenish filaments with no apparent structure inside, it is blue-green
bacteria (sometimes mistakenly called blue-green algae), a Moneran.

Most green protists are flagellates, that is, they move rapidly with
a spiralling motion. Unless you get them to stop, you can't really
see the flagella. Watch out for colonial protists, though, such as
Volvox, which forms a spinning ball of green cells. Don't be fooled
into thinking it is a plant.

Remember, the more you observe the organism, the more sure you
can be. Many living things have stages that make them resemble
members of another kingdom.

Copyright
and Intended Use
Visitors: to ensure that your message is not mistaken for
SPAM, please include the acronym "Bios211" in the subject line
of e-mail communications
Created by David R. Caprette (caprette@rice.edu), Rice University Dates